JPH0412307B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention has no unpleasant odor, has good coating workability, has excellent adhesion to paper, plastic, wood, metal, etc., and has excellent hardening properties, flexibility, water resistance, weather resistance, gloss, corrosion resistance, etc. The present invention relates to an active energy ray-curable coating composition that forms a coating film having the following properties. Conventionally, acrylic resin-based coating compositions containing acrylic resins containing ethylenically unsaturated groups and ethylenically unsaturated monomers as main components have been used as coating compositions that are cured by irradiation with active energy such as ultraviolet rays and electron beams. is commonly used. It has been pointed out that this acrylic resin composition forms a coating film with excellent weather resistance, and has various other problems, and improvements are desired.
That is, the acrylic resin containing an ethylenically unsaturated group has poor compatibility with the ethylenically unsaturated monomer, so that the coating film does not have sufficient gloss. Further, the mixture of both components and the formed coating film generate an unpleasant odor, which is unfavorable from a hygienic point of view in terms of handling. Furthermore, in addition to the above-mentioned defects, the cured coating film obtained by applying the composition to substrates such as paper surfaces such as gift boxes and book covers, printed surfaces, and metal-deposited surfaces has poor adhesion to these substrates. Surface hardening, coating film slipperiness, bendability,
Adhesion to the glue attached to the base material was insufficient for practical use. Furthermore, when the composition is applied to a metal substrate such as iron, zinc, or aluminum,
Adhesion to the base material, water resistance, and corrosion resistance were insufficient. Furthermore, the coating film obtained by applying the composition to plastic (eg, polyurethane resin, etc.) and curing it has poor adhesion to the substrate and flexibility. In addition, the coating film obtained by applying the composition to a wood board that has been treated with a sealant coating and curing it has a good finish, gloss,
It has insufficient adhesion with fillers, curing properties, heat resistance, cold resistance, moisture resistance, etc., and is also poor in its flexibility and cutability with a saw. In view of the above-mentioned situation, the inventors of the present invention have devised a method to cure the acrylic resin composition by irradiating it with active energy rays without reducing its excellent weather resistance.
The purpose is to develop an acrylic resin-based active energy ray-curable coating composition that can eliminate the above-mentioned defects and form a coating film with excellent performance on substrates such as paper, metal, plastic, and wood. He conducted intensive research on the subject. As a result, the above purpose can be achieved by using an unsaturated monomer having a specific structural formula in an acrylic resin containing an ethylenically unsaturated group instead of or in combination with a conventional ethylenically unsaturated monomer. It was found that this could be achieved, and the present invention was completed. That is, the present invention provides (a) general formula (R ₁ is a hydrogen atom or a methyl group, R ₂ is an alkylene group having 2 to 4 carbon atoms, and R ₃ is an alkyl group, phenyl group, or alkylphenyl group having 1 to 20 carbon atoms). The present invention relates to an active energy ray-curable coating composition containing a saturated monomer and (b) an acrylic resin containing an ethylenically unsaturated group as the main components. The coating composition of the present invention is characterized by the combination of the ethylenically unsaturated group-containing acrylic resin [component (b)] and the unsaturated monomer represented by the above general formula [component (a)]. Component (a) is a compound known per se, and in U.S. Pat. No. 4,072,592, it is an adduct of an epoxy resin and acrylic acid, a modified product obtained by further modifying the adduct with an acid anhydride, etc. It is disclosed that a composition using a combination of an unsaturated epoxy resin and the component (a) is cured by irradiation with ultraviolet rays or electron beams. The present inventors also investigated this known technique and found that it was difficult to form a coating film with excellent gloss due to the poor compatibility between component (a) and the unsaturated epoxy resin. They discovered that the film has a serious defect in that it tends to cause cissing. Furthermore, the coating film obtained by applying the composition to a paper surface, wood, etc. and curing it was prone to yellowing, and its adhesion to the ink surface and the sealant was insufficient from a practical point of view. Adhesion to plastics was also unsatisfactory. For metals, it has excellent corrosion resistance and has practical performance, but its high viscosity makes it difficult to apply it to steel pipes. As described above, compositions containing component (a) in combination with unsaturated epoxy resins have various defects in coating film performance, and their range of use is extremely limited. The present inventors have conducted research to eliminate the various defects described above in acrylic resin compositions that are cured by irradiating active energy, and have found that they can be applied in a wide range of applications. By doing so, the object of the present invention was completely achieved. This fact was completely unexpected from the above-mentioned known facts regarding component (a), and a surprising technical effect was obtained. Next, the components constituting the coating composition of the present invention will be explained. (a) Component: General formula (R ₁ is a hydrogen atom or a methyl group, R ₂ is an alkylene group having 2 to 4 carbon atoms, and R ₃ is an alkyl group, phenyl group, or alkylphenyl group having 1 to 20 carbon atoms). Saturated monomer. In the above general formula, the number of carbon atoms in R ₂ is 2 to
Examples of the alkylene group of 4 include ethylene group, n-propylene group, iso-propylene group, n-butylene group, iso-butylene group, and tert-butylene group. If the number of carbon atoms in the alkylene group is 5 or more, curability with active energy rays deteriorates, which is not preferable. In addition, examples of the alkyl group, phenyl group, and alkylphenyl group having 1 to 20 carbon atoms for _R3 include methyl group,
Ethyl group, n-propyl group, i-propyl group,
n-butyl group, i-butyl group, t-butyl group,
i-amyl group, n-hexyl group, n-heptyl group, n-octyl group, 2-ethylhexyl group,
i-nonyl group, lauryl group, stearyl group, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, phenyl group, methylphenyl group, i-propylphenyl group, t-
Examples include butylphenyl group, methoxyphenyl group, etc. If the number of carbon atoms is 21 or more, curability with active energy rays deteriorates, so it is not preferable. In the present invention, as component (a), one or more selected from the unsaturated monomers represented by the above general formula can be used, and among these, in the general formula, R ₁ is a hydrogen atom. , R ₂ is an ethylene group, R ₃ is an n-propyl group, an i-propyl group,
Particular preference is given to using unsaturated monomers represented by n-butyl or phenyl groups. (b) Component: Ethylenically unsaturated group-containing acrylic resin The acrylic resin has an ethylenically unsaturated group in its skeleton, and can be produced by various methods. For example, an unsaturated monomer containing a carboxyl group or a glycidyl group is added to a hydroxyl group-containing acrylic resin to introduce an ethylenically unsaturated group. Examples of the carboxyl group-containing unsaturated monomer include acrylic acid, methacrylic acid, and crotonic acid, and examples of the glycidyl group-containing unsaturated monomer include glycidyl acrylate and glycidyl methacrylate. Alternatively, two or more types can be used. An unsaturated monomer containing a hydroxyl group or a glycidyl group is added to a carboxyl group-containing acrylic resin to introduce an ethylenically unsaturated group. Examples of the hydroxyl group-containing unsaturated monomer include 2-hydroxyethyl acrylate, 2-hydroxyethyl acrylate, and 2-hydroxyethyl acrylate.
-Hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, etc., and the glycidyl group-containing unsaturated monomers include those disclosed above, and one or more selected from these may be used. can. An unsaturated monomer containing a carboxyl group or a hydroxyl group is added to a glycidyl group-containing acrylic resin to introduce an ethylenically unsaturated group. As the carboxyl group-containing unsaturated monomer and the hydroxyl group-containing unsaturated monomer, those disclosed in the above and above can be used, and one or more types selected from these can be used. etc. can be mentioned. In the above ~, the acrylic resin containing a hydroxyl group, a carboxyl group, or a glycidyl group into which an ethylenically unsaturated group is introduced is an unsaturated monomer containing a functional group such as a hydroxyl group, a carboxyl group, or a glycidyl group and other acrylic resins. It can be obtained by copolymerizing it with an unsaturated monomer. As unsaturated monomers containing these functional groups, those disclosed in ~ above can be used, and as other acrylic unsaturated monomers to be copolymerized with these, alkyl acrylic acid or methacrylic acid (having 1 to 1 carbon atoms) can be used. 20 is preferred) ester, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, etc. Examples of alkyl (carbon atoms 1 to 20) esters of acrylic acid or methacrylic acid include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate, n-butyl methacrylate, acrylic isobutyl acid, isomethacrylate
-butyl, tert-butyl acrylate, tert-butyl methacrylate, propyl acrylate, propyl methacrylate, neopentyl acrylate, pentyl methacrylate, hexyl acrylate, hexyl methacrylate, heptyl acrylate, heptyl methacrylate, octyl acrylate , octyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, lauryl acrylate,
Examples include lauryl methacrylate, tetradecyl acrylate, hexadecyl acrylate, hexadecyl methacrylate, hexadel methacrylate, and one or more selected from these can be used. In an acrylic resin containing a hydroxyl group, a carboxyl group, or a glycidyl group, the copolymerization ratio of the unsaturated monomer containing these functional groups and other acrylic unsaturated monomers is determined by the ethylenicity introduced by the above method. It can be arbitrarily selected depending on the amount of unsaturated groups. In addition, in the production of acrylic resins containing these functional groups, in addition to the unsaturated monomers containing these functional groups and other acrylic unsaturated monomers, other polymerizable unsaturated monomers may also be used in combination. Examples of such monomers include styrene, vinyltoluene, methylstyrene, vinyl acetate, vinyl chloride, vinyl isobutyl ether: methyl vinyl ether, and one or more selected from these are combined with both of the above monomers. Based on total amount
Can be used together at a ratio of 40% by weight or less. The copolymerization reaction for producing the acrylic resin containing a hydroxyl group, carboxyl group, or glycidyl group and the method of adding an unsaturated monomer to the acrylic resin to introduce an ethylenically unsaturated group as described above are known methods. It can be done with The component (b) used in the present invention may be any acrylic resin containing an ethylenically unsaturated group, but among them, the number average molecular weight is 1,000 to 30,000, the glass transition temperature is -45 to 70°C (calculated by the Fox formula) ) and those having an ethylenically unsaturated group content of 0.5 to 3.0 mol/Kg are particularly preferred. The coating composition of the present invention essentially contains the above-mentioned components (a) and (b), and the proportion of both components is preferably 5 to 95% by weight, based on the total amount of both components. is in the range of 20 to 80% by weight, and 95 to 5% by weight of component (b), preferably 80 to 20% by weight. If the content of component (a) is less than 5% by weight, the flexibility of the coating film will decrease, while if it exceeds 95% by weight, the curing properties, weather resistance, etc. of the coating film will deteriorate, so both are not preferred. Component (c): Ethylenically unsaturated monomer The above essential components in the composition of the present invention
If necessary, an ethylenically unsaturated monomer [component (c)] can be further used in combination with the system consisting of components (a) and (b). As the component (c), common monomers and oligomers having radical polymerizability can be used, and specific examples include the following. Examples of radically polymerizable monomers include carboxyl group-containing unsaturated monomers, glycidyl group-containing unsaturated monomers, hydroxyl group-containing unsaturated monomers, other acrylic unsaturated monomers, and polymerizations other than these as disclosed in the explanation regarding component (b) above. Examples include sexually unsaturated monomers. Radically polymerizable oligomers are mainly di, tri and tetravinyl compounds, including diethylene glycol diacrylate, diethylene glycol dimethacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, propylene glycol diacrylate, propylene glycol dimethacrylate,
1,3-butanediol diacrylate, 1,3
-Butanediol dimethacrylate, 1,4-butanediol diacrylate, 1,4-butanediol dimethacrylate, neopentyl glycol diacrylate, neopentyl glycol dimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexane Diol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol methacrylate, pentaerythritol trimethacrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, adduct of bisphenol A and ethylene oxide with acrylic acid and/or a product obtained by reacting methacrylic acid, and a product obtained by reacting an adduct of bisphenol A and propylene oxide with acrylic acid and/or methacrylic acid. These monomers and oligomers can be used alone or in combination of two or more. These component (c) can be used in combination in an amount of 5 to 95% by weight, preferably 20 to 80% by weight of the component (b). By using component (c) in combination, the viscosity of the coating composition and the physical performance of the cured coating film can be adjusted. Component (d): Photopolymerization initiator The coating film made from the composition of the present invention is cured by irradiation with active energy such as electron beams and ultraviolet rays. It is necessary to add a polymerization initiator in advance. As the photopolymerization initiator, a usual photopolymerization initiator that is excited by ultraviolet irradiation to generate radicals is used, such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin n-propyl ether, benzoin isopropyl ether, Examples include benzoin n-butyl ether, benzophenone, P-methylbenzophenone, Michler's ketone, acetophenone, 2-chlorothioxanthone, anthraquinone, 2-methylanthraquinone, phenyl disulfide, and 2-nitrofluorene. These photopolymerization initiators can be used alone or in combination of two or more. The amount to be blended is preferably 0.1 to 10% by weight of the total amount of the above-mentioned components (a) and (b), or, if used together with component (c), the total amount thereof. Moreover, in order to promote the photopolymerization reaction by the photopolymerization initiator, a photosensitization accelerator may be used in combination with the photopolymerization initiator. As the photosensitization accelerator, for example, tertiary amine type such as triethylamine, triethanolamine, 2-dimethylaminoethanol, alkylphosphine type such as triphenylphosphine,
Examples include thioethers such as β-thiodiglycol. These photosensitizers may be one or two types.
Can be used in combination with more than one species. The blending amount thereof is preferably 0.1 to 10% by weight of the total amount of component (a) and component (b), or, if component (c) is used in combination, the total amount including the component (a) and (b). As described above, the composition of the present invention essentially contains components (a) and (b), and optionally contains components (c) and/or (d) in combination. Furthermore, the composition can contain pigments and dyes that inhibit the radical polymerization that occurs when irradiated with active energy rays, and also have a low boiling point (180
There is no problem even if a small amount of organic solvent (below ℃) is included. The composition of the present invention can be coated by a roll coater, curtain flow coater, brush, dip, electrostatic coater, spray gun, or the like. The object to be coated is not particularly limited, and it can be applied to plastic, paper, metal-deposited surfaces, metal, wood, etc. Further, the thickness of the coating film on these surfaces to be coated is preferably 3 to 500 μm. The coating film formed from the composition of the present invention is cured by irradiation with active energy rays.
Examples of active energy rays include electron beams and ultraviolet rays, and either of them may be used. Examples of electron beam sources include Kotskucroft type, Kotskucroft-Walton type, Van de Graaff type,
There are resonant transformer types, transformer types, insulated core transformer types, dynamitron types, linear filament types, and high frequency types. The electron beam irradiation conditions are not particularly limited, but a dose of 1 to 20 megarads is suitable. Further, examples of the ultraviolet irradiation source include a mercury lamp, a xenon lamp, a carbon arc, a metal hydride lamp, and sunlight. The irradiation conditions for ultraviolet rays are not particularly limited either, but it is preferable to irradiate in air or under an inert gas atmosphere for several seconds or more.
In particular, when irradiating in air, it is preferable to use a high-pressure mercury lamp. Since the composition of the present invention uses the above-mentioned components (a) and (b), it has been able to obtain various unexpected technical effects. That is, the composition obtained according to the present invention and the cured coating film made from the composition generate no or almost no unpleasant odor, so that the hygienic problem in handling has been solved. Furthermore, since component (a) has excellent compatibility with component (b), it was possible to significantly improve the gloss of the coating film. Moreover, it has excellent adhesion to paper, metal-deposited surfaces, printing ink surfaces, plastics (e.g., polyvinyl chloride, polyurethane, polyester, etc.), wood, and metals, so it has a wider range of applications than conventional acrylic resin paints. became wider. First, when the composition of the present invention is applied to paper, metal-deposited surfaces, ink-printed surfaces, etc. used for cosmetic cases and book covers, a coating film with excellent adhesion and gloss can be formed, and the aesthetics will be significantly improved and the product will last for a long time. Even after a period of time, there will be no shine or yellowing. In addition, the coating film has excellent smoothness, so it does not stick even when stacked or pressed together. Furthermore, since it has excellent flexibility, the coating film will not crack or peel even if it is bent. Moreover, since the composition has a relatively low viscosity, it has good wettability on the surface to be coated, and the coating workability is improved. Furthermore, it has excellent adhesion to plastics and good flexibility, so it can sufficiently respond to these deformations. Furthermore, the composition of the present invention can also be applied to wood,
When active energy is applied to a paint film applied to wood that has undergone sealing treatment, the inside and surface of the paint film is extremely well cured, making it difficult to scratch, improving the finished appearance, gloss, and adhesion with sealants. etc. were improved. Moreover, because the coating film has excellent flexibility, it is easy to cut and process with a saw, etc., and exhibits excellent heat and cold resistance. Furthermore, the water resistance and humidity resistance were also good. Furthermore, the composition of the present invention can also be applied to iron, aluminum, zinc, and alloys containing these metals. The coating films applied to these objects were excellent in terms of adhesion, corrosion resistance, weather resistance, water resistance, etc. Moreover, since the composition of the present invention has a relatively low viscosity, it is most suitable for ironing onto pipes and the like. As described above, the composition of the present invention can be applied to almost any object to be coated and has excellent coating performance. Next, the content of the present invention will be explained in more detail with reference to Examples and Comparative Examples. Note that the present invention is not limited to this example. Parts and % in Examples and Comparative Examples are parts by weight and % by weight. Example 1 (a) Ingredients (b) Component Ethylenically unsaturated group-containing acrylic resin ()
40 parts were mixed to obtain a coating composition targeted by the present invention. The ethylenically unsaturated group-containing acrylic resin (2) was produced in the following manner. 600 parts of methyl methacrylate, 400 parts of methyl acrylate, 600 parts of n-butyl acrylate, 400 parts of glycidyl methacrylate, 2144 parts of toluene,
60 parts of azobisisobutyronitrile was placed in a four-necked flask, stirred, and kept at 110°C for 5 hours to prepare a glycidyl group-containing acrylic resin. To this, 144 parts of acrylic acid and 5 parts of tetraethylammonium bromide were added and kept at 110°C for 2 hours.
After confirming that acrylic acid has undergone a sufficient addition reaction, remove the toluene under reduced pressure and cool the mixture (b).
(number average molecular weight 10,000, glass transition temperature 11°C, ethylenically unsaturated group 0.93 mol/Kg). Example 2 Coating composition obtained in Example 1 100 parts benzophenone [component (d)] 5 parts triphenylphosphine [photosensitization accelerator]
Part 2 Example 3 (a) Ingredients 50 parts (b) Ingredients Ethylenically unsaturated group-containing acrylic resin ()
30 parts (c) Component 20 parts of trimethylolpropane triacrylate were mixed to obtain a coating composition targeted by the present invention. The ethylenically unsaturated group-containing acrylic resin (2) was produced in the following manner. 400 parts of styrene, 600 parts of n-butyl methacrylate
parts, n-butyl acrylate 600 parts, acrylic acid
200 parts of toluene, 1800 parts of toluene, and 90 parts of azobisisobutyronitrile were placed in a four-necked flask and stirred.
The mixture was kept at 110°C for 5 hours to produce a carboxyl group-containing acrylic resin. Next, 380 parts of glycidyl methacrylate and 5 parts of tetraethylammonium bromide were added to this, and the mixture was heated to 110 parts with stirring.
℃ for 2 hours to confirm that the glycidyl methacrylate had sufficiently reacted, the toluene was removed from the solvent under reduced pressure, and the cooled product was used as component (b) (number average molecular weight 6000, glass transition temperature 7℃, ethylene 1.23 mol/Kg). Example 4 Coating composition obtained in Example 3 100 parts Benzoin ethyl ether [component (d)] 5 parts Comparative example 1 Component (a) in the coating composition of Example 1 was replaced with phenoxyethyl acrylate A paint was prepared in accordance with Example 1 except for the following. Comparative Example 2 A coating composition in which component (a) in the coating composition of Example 1 was replaced with diethylene glycol diacrylate, and further 5 parts of benzophenone and 2 parts of triphenylphosphine were blended. Comparative Example 3 A coating composition produced by replacing component (b) in Example 1 with an epoxy resin containing an ethylenically unsaturated group. The ethylenically unsaturated group-containing epoxy resin was produced as follows. Epicote 828 (diglycidyl ether of bisphenol A, epoxy equivalent 185-192, epoxy value 0.50-0.54) 660 parts, acrylic acid 248 parts,
1.3 parts of triethylamine and 0.1 part of hydroquinone
100°C and reacted at the same temperature until the acid value reached 5 to 10. Comparative Example 4 A coating composition in which component (b) in Example 1 was replaced with the ethylenically unsaturated group-containing epoxy resin used in Comparative Example 3, and further 5 parts of benzophenone and 2 parts of triphenylphosphine were blended. Various performance tests were conducted on the coating compositions of Examples and Comparative Examples produced as described above.
The results are shown in Table 1.

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Claims (1)

[Claims] 1 (a) General formula (R ₁ is a hydrogen atom or a methyl group, R ₂ is an alkylene group having 2 to 4 carbon atoms, and R ₃ is an alkyl group, phenyl group, or alkylphenyl group having 1 to 20 carbon atoms). An active energy ray-curable coating composition containing as main components a saturated monomer and (b) an acrylic resin containing an ethylenically unsaturated group.